/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.core.convert.support;

import org.springframework.core.convert.converter.Converter;
import org.springframework.core.convert.converter.ConverterFactory;

/**
 * Converts from a String to a {@link java.lang.Enum} by calling {@link Enum#valueOf(Class, String)}.
 *
 * @author Keith Donald
 * @author Stephane Nicoll
 * @since 3.0
 */
@SuppressWarnings({"rawtypes", "unchecked"})
final class StringToEnumConverterFactory implements ConverterFactory<String, Enum>
{

    @Override
    public <T extends Enum> Converter<String, T> getConverter(Class<T> targetType)
    {
        return new StringToEnum(ConversionUtils.getEnumType(targetType));
    }


    private static class StringToEnum<T extends Enum> implements Converter<String, T>
    {

        private final Class<T> enumType;

        public StringToEnum(Class<T> enumType)
        {
            this.enumType = enumType;
        }

        @Override
        public T convert(String source)
        {
            if (source.isEmpty())
            {
                // It's an empty enum identifier: reset the enum value to null.
                return null;
            }
            return (T) Enum.valueOf(this.enumType, source.trim());
        }
    }

}
